I recommend StudioPress/Genesis for most clients who want to get up and running quickly. They focus on good coding practices, and have regular security audits by core WordPress developers (the folks who write WordPress itself). I have a lifetime developer license for their in-house themes, so if you want to use any of these they would be free to you. They also sell third-party themes that you would need to purchase your own license for. Browse their themes (affiliate link)
Ready to move beyond pre-packaged themes and get your own unique design? I can help you find the imagery that conveys your passion and purpose. My approach blends my design and marketing experience with an intuitive sense of who you are. My design style is simple, clean, and straightforward.